The move is necessary, she said Monday, to save net neutrality and protect Internet users. But Republicans and business groups warn that applying utility-style regulations to the Internet would strangle economic growth and ultimately mean worse Internet service.

"I oppose special Internet fast lanes, only open to those firms large enough to pay big money or fraught enough to give up big stakes in their company," the California Democrat wrote in a letter to Federal Communications Commission Chairman Tom Wheeler, urging him to classify broadband as a "telecommunications service" under Title II of the Communications Act.

Pelosi is the latest—and highest-ranking—Democrat to back the controversial regulatory maneuver. Her position puts more political pressure on Wheeler and the other commission Democrats to invoke the powers.